The Apple Power Mac Processor Upgrade (APMPU) is a PowerPC 601 upgrade for 68040-based Macs that have a 32-bit LC processor direct slot (PDS) – the Quadra 605/LC 475/Performa 475-476, LC 575/Performa 575-578, LC 580/Performa 580-588, and Quadra 630/LC 630/Performa 630 series.